Battery assembly with temperature control device

ABSTRACT

A battery module of the present invention is adaptable to be utilized in various configurations including and not limited to an overlapping battery cell packaging configuration and a vertical stack battery cell packaging configuration used in an automotive and non-automotive applications. The battery module has a plurality of battery heatsink assemblies with the cells disposed therebetween. A plurality of rods extend through the each heatsink assemblies to secure the heatsink assemblies and the cell with one another to form the battery module.

FIELD OF THE INVENTION

The subject invention relates to battery packs having cells and moreparticularly, to a battery pack for electric/hybrid vehicles having acooling system or a heating system for cooling the cells within thebattery pack and method of retaining the cells within the battery pack.

BACKGROUND OF THE INVENTION

Motor vehicles, such as, for example, hybrid vehicles use multiplepropulsion systems to provide motive power. This most commonly refers togasoline-electric hybrid vehicles, which use gasoline (petrol) to powerinternal-combustion engines (ICEs), and electric batteries to powerelectric motors. These hybrid vehicles recharge their batteries bycapturing kinetic energy via regenerative braking. When cruising oridling, some of the output of the combustion engine is fed to agenerator (merely the electric motor(s) running in generator mode),which produces electricity to charge the batteries. This contrasts withall-electric cars which use batteries charged by an external source suchas the grid, or a range extending trailer. Nearly all hybrid vehiclesstill require gasoline as their sole fuel source though diesel and otherfuels such as ethanol or plant based oils have also seen occasional use.

Batteries and cells are important energy storage devices well known inthe art. The batteries and cells typically comprise electrodes and anion conducting electrolyte positioned therebetween. Battery packs thatcontain lithium ion batteries are increasingly popular with automotiveapplications and various commercial electronic devices because they arerechargeable and have no memory effect. Operating the lithium ionbattery at an optimal operating temperature is very important to thebatteries performance and lifespan.

Due to the characteristics of the lithium ion batteries, the batterypack is typically specified to operate—within an approximate ambienttemperature range of −30° C. to 60° C. However, even when operatingwithin this temperature range, the battery pack may begin to lose itscapacity or ability to charge or discharge should it remain at theextremes for long periods of time. Nonetheless, it may be unavoidablethat the lithium ion battery be used where the ambient temperature fallsoutside the temperature range.

Alluding to the above, significant temperature variances can occur fromone cell to the next, which is detrimental to performance of the batterypack. To promote long life of the entire battery pack, the cells must bebelow a desired threshold temperature. To promote pack performance, thedifferential temperature between the cells in the battery pack should beminimized. However, depending on the thermal path to ambient, differentcells will reach different temperatures. Further, for the same reasons,different cells reach different temperatures during the chargingprocess. Accordingly, if one cell is at an increased temperature withrespect to the other cells, its charge or discharge efficiency will bedifferent, and, therefore, it may charge or discharge faster than theother cells. This will lead to decline in the performance of the entirepack.

The art is replete with various designs of the battery packs withcooling and packaging systems. The U.S. Pat. No. 5,071,652 to Jones etal. teaches a metal oxide-hydrogen battery including an outer pressurevessel of circular configuration that contains a plurality of circularcell modules disposed in side-by-side relations. Adjacent cell modulesare separated by circular heat transfer members that transfer heat fromthe cell modules to the outer vessel. Each heat transfer member includesa generally flat body or fin which is disposed between adjacent cellmodules. A peripheral flange is located in contact with the innersurface of the pressure vessel. The width of each cell module is greaterthan the length of the flange so that the flange of each heat transfermember is out of contact with the adjacent heat transfer member. Theflanges are constructed and arranged to exert an outward radial forceagainst the pressure vessel. Tie bars serve to clamp the cell modulesand heat transfer members together in the form of a stack which isinserted into the pressure vessel.

The metal oxide-hydrogen battery taught by the U.S. Pat. No. 5,071,652to Jones et al. is designed for cylindrical type of batteries andteaches the heat transfer members in direct contact with the vesselthereby failing to create a clearance between the vessel and the heattransfer members, which can be used to introduce cooling or heatingagent to cool or heat the cells.

Referring now to packaging systems of the battery cells, numerous priorart references teach metallic cases used to protect the cells fromhandling and vibration damage and allowing for combining of multiplecases into a single large pack. However, the metallic cases areexpensive to manufacture and each different configuration requires newdies to produce the various components and new tools to assemble thosecomponents. Consequently, techniques and materials for enclosing thebattery cells in envelopes creating lithium battery cell packs have beendeveloped. Unfortunately, these packages do not provide structuralrigidity or protection from handling and vibration nearly as well as themetallic cases, nor can they be combined into consistently sized groupsof cells because of the inherent variation in the thickness of a lithiumbattery cell pack.

There remains an opportunity for an improved battery pack having cellretaining elements to maintain the battery pack at the optimal operatingtemperature to ensure the longest possible life cycle, with ratedcapacity, and charge and discharge rates.

SUMMARY OF THE INVENTION

A battery module of the present invention is adaptable to be utilized invarious configurations including and not limited to a horizontally orvertically stacked battery cell packaging configurations used inautomotive and non-automotive applications. The battery module has amultitude of cells each adjacent to a respective heatsink—formed fromthermally conductive materials such as, for example, flat stock aluminumalloy foils and the like, without limiting the scope of the presentinvention. Preferably, each cell is a lithium ion cell having a firstcurrent collector and a first electrode adjacent the first currentcollector and a second current collector and a second electrode ofcharge opposite from the first electrode and adjacent the second currentcollector. A separator layer is positioned between the first and secondelectrodes with the first and second electrodes conducting electrolytetherebetween. The plurality of the first electrodes and the secondelectrodes are stacked and packaged into an electrical insulatingenvelope to form a cell.

Alluding to the above, each heatsink presents a plate formed fromthermally conductive materials. The plate defines thermal transfer edgesand terminal ends. Each plate defines a cut out portion and a spacerengaging said cut out portions. Each plate includes a plurality of holesto receive a plurality of rods extending therethrough to interconnectthe heat sinks with one another to form the battery pack. One of theterminal ends extends into a fin presenting a first configuration havinga rectangular cross section. The other terminal end extends into anotherfin presenting a second configuration having a L-shaped cross section.The first and second cross sections are not intended to limit the scopeof the present invention and are disclosed herewith for exemplarypurposes. The fins may be cold formed and are designed to transfer heateither to or from the cells depending on application.

A cell retaining device is cooperable with each heat sink. The cellretaining device includes a inner frame set and a outer frame set. Theinner frames of each cell retaining device sandwiches the heat sinktherebetween. The inner and outer frames present a plurality of male andfemale connecting features that mechanically engaged with one another tolock the prismatic cell within the inner and outer frames.—Thesefeatures can be disengaged to allow for the removal of the prismaticcell for disassembly purposes. This describes a cell retaining and heattransfer assembly

A device, such as a layer of material, such as foam or any othernon-rigid polymeric material, is sandwiched between the prismatic cells.The device substantially covers the prismatic cells. Each heat sink hasa pair of the inner frames and is connected to the opposite sides of theheat sink and mechanically engaging the respective outer frames havingthe respective prismatic cells in between to form a cell retaining andheat transfer assembly. This device is sandwiched between at least twoof these assemblies which are mechanically stacked and electricallyconnected to one another to form the battery pack. As the assemblies arecombined to form the battery pack, the device allows expansion andcontraction of the prismatic cells during typical charge and dischargestates therefore causing the cell to maintain intimate contact with theheat sink for efficient thermal transfer.

An advantage of the present invention is to provide a battery packhaving excellent retention that surrounds and secures the cells.

Another advantage of the present invention is to provide a battery packthat reduces manufacturing costs due to simplified assembly methods.

Still another advantage of the present invention is to provide a meansto thermally manage the battery pack to deliver and receive high ratesof current; i.e. the C-rate, by efficiently removing undesired heatduring the rapid charge or discharge pulse that may negatively impactthe performance and life span of the battery pack.

Still another advantage of the present invention is to provide a packthat is simple in design and has a reduced mass.

Still another advantage of the present invention is to provide a batterypack that is easily expandable for varying applications.

Still another advantage of the present invention is to provide anelectrically insulating shell the surrounds the prismatic cells.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated asthe same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 illustrates a battery case having a pair of battery packs of thepresent invention;

FIG. 2 illustrates a heat sink sandwiched between a pair of innerframes;

FIG. 3 illustrates a fragmental perspective view of the heat sinksandwiched between the inner frames as shown in FIG. 2;

FIG. 4 illustrates an exploded view of FIG. 2;

FIG. 5 illustrates a perspective view of a cell retaining element havingthe heat sink sandwiched between the inner frames, a pair of prismaticcells positioned on opposite sides of the heat sink with each prismaticcell extending over the respective inner frames and a pair of outerframes each extending over the respective prismatic cell;

FIG. 6 illustrates an exploded view of the cell retaining element shownin FIG. 5; and

FIG. 7 illustrates a perspective and exploded view of one of the batterymodule including a plurality of the cell retaining elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the Figures, wherein like numerals indicate like orcorresponding parts, a battery assembly of the present invention isgenerally indicated at 10 in FIG. 1 having a pair of battery packs,generally indicated at 12, disposed in a housing 14. The battery pack 12is adaptable to be utilized in various configurations including and notlimited to a horizontally or vertically stacked battery cell packagingconfiguration used in an automotive vehicle applications ornon-automotive applications. Each battery pack 12 includes a pluralityof cells 16. Preferably, each cell 16 is a lithium ion cell having aprismatic configuration without limiting the scope of the presentinvention. Those skilled in the battery art will appreciate that othercells can be utilized with the present invention. Each cell 16 includesa plurality of battery components (not shown) co-acting between oneanother with electrolyte therebetween as known to those skilled in thelithium battery art. A first electrode is adjacent a first currentcollector and a second electrode of charge opposite from the firstelectrode is adjacent a second current collector. A separator layer ispositioned between the first and second electrodes with the first andsecond electrodes with electrolyte therebetween. A plurality of firstelectrodes and second electrodes are stacked and packaged into anelectrical insulating envelope to form a cell.

Alluding to the above, each cell 16 presents side edges 18 and 20. Afirst terminal or first bend 22 presents a positive terminal and extendsfrom one of the edges 18. A second terminal or bend 24 presents anegative terminal extending from the other edge 20. Each bend 22 and 24defines an angle of at least ninety degrees. The angle may vary at itsdegree and may be configured to be up to ninety degrees without limitingthe scope of the present invention. Alternatively, the first and secondterminals may present a planar configuration. Each bend 22 and 24presents a pair of semicircular openings 26. Alternatively, each bendmay present other openings (not shown) having different configurationswithout limiting the scope of the present invention.

Referring now to FIGS. 2 through 6, each battery pack includes aplurality of cell retaining elements, generally shown at 30, removeablyconnected with one another to form the battery pack 12. FIG. 7illustrates an exploded view of the battery pack 12 to appreciate theinventive concept. The cell retaining element 30 includes a heatsink,generally indicated at 32. The heatsink 32 presents a plate 34 formedfrom a thermally conductive material such as aluminum, copper, and thelike, without limiting the scope of the present invention. Each heatsink32 terminates to oppositely spaced from one another fin portions,generally indicated at 36 and 38 in FIG. 4. The fin portion 38 presentsa rectangular or tubular cross section 40. The other fin portion 36presents a flat surface 42. The fin portions 36 and 38 may include agate shape, may be pleated, planar, may present a plurality of slots orholes, may be formed as a bend to provide a thermal interface plane foran external heating or cooling device including but not limited toheater blankets and/or cooling jackets. Those skilled in the art willappreciate that numerous other shapes of the fin portions 36 and 38 canbe utilized to provide better surface area for cooling or heating media,such as liquids, solids, or gasses, and the like, are introduced to thefin portions 36 and 38 of each thermally conductive plate, sheet, orfoil to either cool or to heat the cells 16. The fin portions 36 and 38may be cold formed and are designed to transfer heat either to or fromthe cells depending on application. The plate 34 defines a plurality ofslots 43 and semicircular configuration 44 at the sides 46 of the plate34 to receive a plurality of rods 48 extending therethrough tointerconnect the cell retaining elements 30 with one another to form thebattery pack 12.

As best illustrated in FIGS. 4 through 7, a frame assembly of the cellretaining element 30 is disclosed. The frame assembly includes a firstset of inner frames 50 and 52 securing the plate 34, sandwiched betweenthe inner frames 50 and 52, and a second set of outer frames 54 and 56for securing the cells 16. One of the cells 16 is secured between one ofthe inner frames 50 and one of the outer frames 54. The other inner andouter frames 52 and 56 secure another of the cells 16 retainedtherebetween.

As best shown in FIG. 4, one of the inner frames 50 presents aperipheral edge 58 and side walls 60 and 62. One of the side walls 62includes a pair of pins 64 and 66 to electro-mechanically engage thebends 22 or 24 of the cells 16. A plurality of holes or femaleconnectors 68 are defined in the inner frame 50. A plurality of maleconnectors or hooks 70 are formed and integrally extend from and aboutthe peripheral edge 58 of the inner frame 50. The hooks 70 extend in theopposite direction and away from the plate 34. A plurality of studs 72extend from the inner frame 50 in the direction opposite from the hooks70 to mechanically engage another inner frame 52 and the plate 34sandwiched therebetween.

As best illustrated in FIG. 6, another inner frame 52 presents aconfiguration similar to the configuration of inner frame 52. The innerframe 52 includes a peripheral edge 80 and side walls 82 and 84. One ofthe side walls 82 may also includes a pair of pins (not shown) toelectro-mechanically engage the bends 22 or 24 of the cells 16. Aplurality of holes or female connectors 86 are defined in the frame 52.A plurality of male connectors or hooks 88 are formed and integrallyextend from and about the peripheral edge 58 of the frame 50. The hooks88 extend in the opposite direction and away from the plate 34. Aplurality of studs 89 extend from the inner frame 52 in the directionopposite from the hooks 88 to mechanically engage the inner frame 50 andthe plate 34 sandwiched therebetween. The frames 50 and 52 are moldedfrom a polymeric material. Those skilled in the art will appreciate thatvarious polymeric materials may be used to form the frames 50 and 52without limiting the scope of the present invention. The frames 50 and52 may be partially formed from the polymeric material and have thehooks and studs disposed therein during the molding stage, wherein thehooks and studs may be formed from a non-polymeric material. The moldingmay be injection molding or cast molding. The materials and methods offormation of the lower frames 50 and 52 are used for exemplary purposesand are not intended to limit the scope of the present invention.

As best shown in FIG. 6, one of the outer frames 54 presents aperipheral edge 90 and side walls 92 and 94 each presenting cut outportions 96 and 98 dimensionally configured to engage the bends 22and/or 24. A plurality of holes or female connectors 100 are defined inthe frame 54. A plurality of female connectors 102 are formed in theperipheral edge 90 to engage the hooks 70 extending from the inner frame50 in a snap interface to secure one of the prismatic cells 16therebetween. The outer frame 54 and the inner frame 50 define anopening to surround the raised portions 104 of the cell 16 andsandwiched a peripheral lip portion 106 of the cell 16 therebetween. Oneof the raised portions 104 of each cell 16 frictionally engaged theplate 34 while the other raised portion 104 frictionally engages theraised portion 104 of another cell 16 retained by adjacent cellretaining element, as best shown in FIG. 7.

Alternatively, as best shown in FIG. 7, a device or a layer of material110, such as foam or any other non-rigid polymeric materials, issandwiched between the raised portions 104 of the prismatic cells 16.The device 110 substantially covers the raised portions 104 of theprismatic cell 16. Alternatively, the device 110 is sandwiched betweenthe peripheral lip portion 106 of the cell 16 and the upper frame 54 tomechanically retain the device 110 with the cell retaining element 30.As the cell retaining elements 30 are assembled with one another to formthe battery pack 12, the cell 16 of one cell retaining element 30 isplaced adjacent the cell 16 of adjacent cell retaining element 30wherein the device 110 is sandwiched between the prismatic cells 16. Asthe cell retaining elements 30 are combined to form the battery pack 12,the device 110 allows expansion and contraction of the prismatic cells16 during typical charge and discharge states therefore causing the cell16 to maintain intimate contact with the heat sink 34 for efficientthermal transfer inside the battery pack 12 and/or battery assembly 10.

Similarly, the other outer frame 56 presents a peripheral edge 112 andside walls 114 and 116 each presenting cut out portions 118 and 120dimensionally configured to engage the bends 22 and/or 24. A pluralityof holes or female connectors 122 are defined in the frame 56. Aplurality of female connectors 124 are formed in the peripheral edge 112to engage the hooks 88 extending from the inner frame 52 to secure oneof the prismatic cells 16 in a snap interface therebetween. The outerframe 56 and the inner frame 52 define an opening to surround the raisedportions 104 of another prismatic cell 16 and sandwiched a peripherallip portion 106 of the prismatic cell 16 therebetween.

One of the raised portions 104 of the prismatic cell 16 frictionallyengaged the plate 34 while the other raised portion 104 frictionallyengages the raised portion 104 of another cell 16 retained by adjacentcell retaining element, as best shown in FIG. 7. The outer frames 54 and56 are molded from a polymeric material. Those skilled in the art willappreciate that various polymeric materials may be used to form theframes 54 and 56 without limiting the scope of the present invention.The frames 54 and 56 may be partially formed from the polymeric materialand have the hooks and studs disposed therein during the molding stage,wherein the hooks and studs may be formed from a non-polymeric material.The molding may be injection molding or cast molding. The materials andmethods of formation of the inner frames 54 and 56 are used forexemplary purposes and are not intended to limit the scope of thepresent invention.

While the invention has been described as an example embodiment, it willbe understood by those skilled in the art that various changes may bemade and equivalents may be substituted for elements thereof withoutdeparting from the scope of the invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the invention without departing from the essentialscope thereof. Therefore, it is intended that the invention not belimited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A battery assembly comprising: at least one battery pack; a pluralityof prismatic cells of said at least one battery pack; and at least onecell retaining element extending between two of said prismatic cells andpresenting a pair of mechanical devices with one of said devicesmechanically engaging one of said prismatic cells and another of saiddevices mechanically engaging the other of said prismatic cells therebylocking said prismatic cells with said cell retaining element andforming contact between said at least one cell retaining element andsaid prismatic cells for manipulating temperature of said prismaticcells through said at least one cell retaining element.
 2. A batteryassembly as set forth in claim 1 wherein one of said mechanical devicesis further defined by a plate formed from at least one of thermallyconductive materials.
 3. A battery assembly as set forth in claim 1wherein said at least one cell retaining element is further defined by apair of first frames with said plate being sandwiched between said pairof first frames.
 4. A battery assembly as set forth in claim 3 whereineach of said first frames includes a peripheral edge, a plurality ofmale connectors extending from each of said first frames, a plurality offemale connectors defined in each of said first frames.
 5. A batteryassembly as set forth in claim 4 wherein each of said first framesincludes at least one pin extending therefrom to mechanically engage oneof said female connectors defined in another of said first framesthereby sandwiching said plate between said first frames.
 6. (canceled)7. A battery assembly as set forth in claim 1 wherein each of saidprismatic cells includes raised portions extending to a peripheral Hpportion, a negative terminal and a positive terminal.
 8. A batteryassembly as set forth in claim 4 wherein each of said first framesincludes a pair of studs extending from said peripheral edge of eachsaid first frame to engage at least one positive terminal and/ornegative terminal.
 9. A battery assembly as set forth in claim 3 whereinanother of said mechanical devices is further defined by a pair ofsecond frames.
 10. A battery assembly as set forth in claim 9 whereineach of said second frames includes a peripheral edge and a plurality offemale connectors defined in each of said second frames.
 11. A batteryassembly as set forth in claim 10 wherein each of said second frames aremechanically engaged with said first frames, respectively, for retainingtwo of said prismatic cells with said plate engaging raised portions ofeach of said prismatic cells.
 12. (canceled)
 13. A battery assembly asset forth in claim 2 including a device sandwiched between each of saidcell retaining elements for allowing expansion and contraction of saidprismatic cells during charge and discharge states therefore causingsaid prismatic cell to maintain intimate contact with said plate forefficient thermal transfer.
 14. A battery assembly as set forth in claim7 wherein said device is further defined by a layer of expandablematerial substantially covering said raised portion of each saidprismatic cell.
 15. A battery assembly as set forth in claim 14 whereinsaid layer is equally disposed between said peripheral lip portion ofsaid prismatic cell and one of said second frames.
 16. A method offorming a battery assembly comprising the steps of: forming at least onebattery pack by connecting a plurality of prismatic cells with oneanother; placing at least one cell retaining element between two of theprismatic cells; connecting a pair of mechanical devices to the cellretaining element with one of the devices mechanically engaging one ofthe prismatic cells and another of the devices mechanically engaging theother of the prismatic cells; and locking the prismatic cell with thecell retaining element by the devices to form contact between at leastone cell retaining element and the prismatic cells to manipulatetemperature of the prismatic cell through at least one cell retainingelement.
 17. A method as set forth in claim 16 wherein the step ofconnecting a pair of mechanical devices is further defined by connectinga pair of first frames with a plate of the cell retaining elementwherein the plate is sandwiched between the pair of the first frames.18. A method as set forth in claim 17 including the step of forming aplurality of male connectors extending from each of the first frames andforming a plurality of female connectors defined in each of the firstframes, and at least one pin extending from each of the first frames tomechanically engage the frames with one another with the platesandwiched between the first frames.
 19. (canceled)
 20. A method as setforth in claim 18 including the step of forming a pair of second frameshaving a plurality of female connectors defined in each of the secondframes.
 21. A method as set forth in claim 20 including the step ofmechanically engaging the second frames with the first frames,respectively, to retain two of the prismatic cells with the plate.
 22. Amethod as set forth in claim 16 including the step of placing a devicebetween each of the cell retaining elements, wherein the device ismovable between an expanded mode and a contracted mode to form clearancebetween the prismatic cells as at least one of the prismatic cellsexpands during operational mode of the battery pack.
 23. A method as setforth in claim 16 including the step of forming the device from a layerof expandable material substantially covering the prismatic cell.
 24. Abattery assembly comprising: at least one battery pack; a plurality ofprismatic cells of said at least one battery pack; a pair of heattransfer elements each extending between two of said prismatic cells;and a pair of cell retaining devices connecting one of said heattransfer elements with at least one of said prismatic cells, each cellretaining device presenting a first frame and a second frame each havinga pair of first and second mechanical connectors for removeably engagingsaid at least one prismatic cell with said heat transfer element as eachof said first connectors mechanically engage with each of said secondconnectors thereby locking said at least one prismatic cell within saidfirst and second frames and to said heat transfer element.
 25. A batteryassembly as set forth in claim 24 wherein said heat transfer element isfurther defined by a plate formed from at least one of thermallyconductive materials.
 26. A battery assembly as set forth in claim 24wherein each of said first frames includes a peripheral edge, aplurality of male connectors extending from each of said first frames, aplurality of female connectors defined in each of said first frames. 27.A battery assembly as set forth in claim 26 wherein each of said firstframes includes at least one pin extending therefrom to mechanicallyengage one of said female connectors defined in another of said firstframe thereby sandwiching said plate between said first frames. 28.(canceled)
 29. A battery assembly as set forth in claim 25 wherein eachof said prismatic cells includes raised portions extending to aperipheral lip, a negative terminal and a positive terminal.
 30. Abattery assembly as set forth in claim 26 wherein each of said firstframes include a pair of studs extending from said peripheral edge ofeach said first frame to engage at least one of said positive terminalsand said negative terminals.
 31. A battery assembly as set forth inclaim 24 wherein each of said second frames includes a peripheral edgeand a plurality of female connectors defined in each of said secondframes.
 32. A battery assembly as set forth in claim 29 wherein each ofsaid second frames are mechanically engaged with said first frames,respectively, for retaining two of said prismatic cells with said plateengaging raised portions of each of said two prismatic cells. 33.(canceled)
 34. A battery assembly as set forth in claim 24 including adevice sandwiched between each of said heat transfer elements, saiddevice movable between an expanded mode and a contracted mode therebyforming clearance between said prismatic cells as at least one of saidprismatic cells expands during operational mode of said battery pack.35. A battery assembly as set forth in claim 29 wherein said device isfurther defined by a layer of expandable material substantially coveringsaid raised portion of each said prismatic cell.
 36. A battery assemblyas set forth in claim 35 wherein said layer is equally disposed betweensaid peripheral lip portion of said prismatic cell and one of saidsecond frames.
 37. A battery assembly comprising: at least one batterypack; a plurality of prismatic cells of said at least one battery pack;a pair of heat transfer elements each extending between two of saidprismatic cells; and a pair of cell retaining devices connecting one ofsaid heat transfer elements with at least one of said prismatic cells,and a device sandwiched between each of said heat transfer elements,said device movable between an expanded mode and a contracted modethereby forming clearance between said prismatic cells as at least oneof said prismatic cells expands during operational mode of said batterypack.
 38. A battery assembly as set forth in claim 37 wherein each saidcell retaining device presenting a first frame and a second frame eachhaving a pair of first and second connectors for removeably engagingsaid at least one prismatic cell with said heat transfer element as eachof said first connectors mechanically engage with each of said secondconnectors thereby locking said at least one prismatic cell within saidfirst and second frames and to said heat transfer element.
 39. A batteryassembly as set forth in claim 37 wherein said device is further definedby a layer of expandable material substantially covering a raisedportion of each said prismatic cell.
 40. A battery assembly as set forthin claim 39 wherein said layer is equally disposed between a peripherallip portion of said prismatic cell and one of said second frames.
 41. Abattery assembly as set forth in claim 37 wherein said heat transferelement is further defined by a plate formed from at least one ofthermally conductive materials.
 42. A battery assembly as set forth inclaim 38 wherein each of said first frames includes a peripheral edge, aplurality of male connectors extending from each of said first frames, aplurality of female connectors defined in each of said first frames. 43.A battery assembly as set forth in claim 42 wherein each of said firstframes includes at least one pin extending therefrom to mechanicallyengage one of said female connectors defined in another of said firstframe thereby sandwiching said plate between said first frames. 44.(canceled)
 45. A battery assembly as set forth in claim 42 wherein eachof said prismatic cells includes raised portions extending to aperipheral lip, a negative terminal and a positive terminal.
 46. Abattery assembly as set forth in claim 45 wherein each of said firstframes include a pair of studs extending from said peripheral edge ofeach said first frame to engage at least one of said positive terminalsand said negative terminals.
 47. A battery assembly as set forth inclaim 38 wherein each of said second frames includes a peripheral edgeand a plurality of female connectors defined in each of said secondframes.
 48. A battery assembly as set forth in claim 38 wherein each ofsaid second frames are mechanically engaged with said first frames,respectively, for retaining two of said prismatic cells with said plateengaging raised portions of each of said two prismatic cells. 49.(canceled)